Question

describe the digestive systems of non-ruminant herbivores, ruminant herbivores, birds, and carnivores. And describe the special type of behavior exhibited by lagomorphs.

Answer 1

Ruminant herbivores digestive system has 4 compartments namely-

Rumen where microbial fermentation occurs

Reticulum,

Omasum, responsible for absorption of volatile fatty acids

Obasum that is the true stomach.

Fermentation in rumen and reticulum is for microbial activity on complex carbohydrates like cellulose in anaerobic environment at 100 to 108degree F and pH of 6 to 6.4.

breakdown products of food are mixed with saliva forming cud that is regurgitated and further broken down. cellulose , hemicellulose are broken in these chambers by bacteria into volatile fatty acids. Proteins and certain carbohydrates are also fermented.

Degraded digesta is then passed into omasum absorbs volatile fatty acids and remaining directed to true stomach. This compartments' release enzymes and acids that will ultimately digest the food as well as microbes produced in rumen. The digesta will pass to small intestine for nutrient absorption in large surface area created due to presence of villi. Then in large intestine fiber is broken down by microbial fermentation, water and mineral absorption occurs. Waste is also expelled from here.

Non ruminants digestive system does not have other compartments like rumen, reticulum, etc . They only have stomach, small intestine, large intestine and hence cannot digest complex carbohydrates like cellulose and hemicellulose.

Birds have two portions of stomach. Proventriculus and muscular portion that is called gizzard. Gizzard has same functionas that of mammalian teeth for grinding and chewing food. Hence, they can eat unmasticated food. Chemical digestion and absorption occurs in intestine and removal of waste occurs from cloaca.

Carnivores have one stomach chamber , that is a simple digestive system , have pointed sharp teeth for tearing flesh.

Lagomorphs have 4 incisors in upper jaw and they grow continuously. Hence, they chew fibrous food preventing them from growing too long. They have caecum where food is mixed with bacteria, and other microbes to digest cellulose. This is called hind gut fermentation. Fecal matter passes through colon.